The invention is a window comparator for determining when an input signal is between two limits.
In the prior art, a window comparator includes a pair of comparison circuits arranged with two pairs of input terminals so that input signals applied to one terminal of each pair are compared with a different fixed reference, or bias, voltage applied to the other terminal of each pair. The input signals therefore are always compared with the fixed reference voltages. Thus the prior art circuitry is single-ended in nature and cannot reject common-mode variations in the input signals while maintaining a fixed difference between the two limits. When implemented in integrated circuit form, the prior art window comparator requires a large area of integrated circuit chip.